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scsi: target: core: Fix backend plugging

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target_core_iblock is plugging and unplugging on every command and this is
causing perf issues for drivers that prefer batched cmds. With recent
patches we can now take multiple cmds from a fabric driver queue and then
pass them down the backend drivers in a batch. This patch adds this support
by adding 2 callouts to the backend for plugging and unplugging the
device. Subsequent commits will add support for iblock and tcmu device
plugging.

Link: https://lore.kernel.org/r/20210227170006.5077-22-michael.christie@oracle.com
Reviewed-by: Bodo Stroesser <bostroesser@gmail.com>
Signed-off-by: Mike Christie <michael.christie@oracle.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
This commit is contained in:
Mike Christie 2021-02-27 11:00:02 -06:00 committed by Martin K. Petersen
parent 802ec4f672
commit 302990ac3b
3 changed files with 48 additions and 1 deletions
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43
drivers/target/target_core_transport.c
View File

@ -1807,10 +1807,42 @@ void target_submit_cmd(struct se_cmd *se_cmd, struct se_session *se_sess,
}
EXPORT_SYMBOL(target_submit_cmd);
static struct se_dev_plug *target_plug_device(struct se_device *se_dev)
{
struct se_dev_plug *se_plug;
if (!se_dev->transport->plug_device)
return NULL;
se_plug = se_dev->transport->plug_device(se_dev);
if (!se_plug)
return NULL;
se_plug->se_dev = se_dev;
/*
* We have a ref to the lun at this point, but the cmds could
* complete before we unplug, so grab a ref to the se_device so we
* can call back into the backend.
*/
config_group_get(&se_dev->dev_group);
return se_plug;
}
static void target_unplug_device(struct se_dev_plug *se_plug)
{
struct se_device *se_dev = se_plug->se_dev;
se_dev->transport->unplug_device(se_plug);
config_group_put(&se_dev->dev_group);
}
void target_queued_submit_work(struct work_struct *work)
{
struct se_cmd_queue *sq = container_of(work, struct se_cmd_queue, work);
struct se_cmd *se_cmd, *next_cmd;
struct se_dev_plug *se_plug = NULL;
struct se_device *se_dev = NULL;
struct llist_node *cmd_list;
cmd_list = llist_del_all(&sq->cmd_list);
@ -1819,10 +1851,19 @@ void target_queued_submit_work(struct work_struct *work)
return;
cmd_list = llist_reverse_order(cmd_list);
llist_for_each_entry_safe(se_cmd, next_cmd, cmd_list, se_cmd_list)
llist_for_each_entry_safe(se_cmd, next_cmd, cmd_list, se_cmd_list) {
if (!se_dev) {
se_dev = se_cmd->se_dev;
se_plug = target_plug_device(se_dev);
}
target_submit(se_cmd);
}
if (se_plug)
target_unplug_device(se_plug);
}
/**
* target_queue_submission - queue the cmd to run on the LIO workqueue
* @se_cmd: command descriptor to submit

2
include/target/target_core_backend.h
View File

@ -34,6 +34,8 @@ struct target_backend_ops {
int (*configure_device)(struct se_device *);
void (*destroy_device)(struct se_device *);
void (*free_device)(struct se_device *device);
struct se_dev_plug *(*plug_device)(struct se_device *se_dev);
void (*unplug_device)(struct se_dev_plug *se_plug);
ssize_t (*set_configfs_dev_params)(struct se_device *,
const char *, ssize_t);

4
include/target/target_core_base.h
View File

@ -770,6 +770,10 @@ struct se_cmd_queue {
struct work_struct work;
};
struct se_dev_plug {
struct se_device *se_dev;
};
struct se_device_queue {
struct list_head state_list;
spinlock_t lock;